Spectral Characterization Of The Interaction Of Porphyrin And Metalloporphyrin With Biomacromolecule

Chapterl The structural characteristics and physi-chemical properties of porphyrin and its metal derivatives, and the structural characteristics and biochemical properties of three kinds of important biomacromolecules, i.e. DNA, protein and biomembrane have been introduced briefly. The outline of interactions of porphyrin and its metal derivatives with DNA, protein and biomembrane have been reviewed, respectively. The recent applications of porphyrin and its supramolecular systems in the field of photodynamic therapy and molecular recognition have been reviewed. Furthermore, the meaning, the main contents and the innovation of this research work have been addressed.Chapter2 By taking advantage of the deprotonation property of the amphiphilic porphyrin, meso-tetrakis(4-hydroxyphenyl) porphyrin (THPP), and the spectral sensitivity to the microenvironment of the porphyrin moiety, a pH-controlled transmembrane process has been investigated by means of UV-Visible spectrum. With the increasing of pH values, the Soret band shifts from 424nm to 439nm, and the four Q bands (520nm, 561nm, 595nm, 653nm) are disappeared while two new Q bands are appeared at 580nm and 667nm, which is similar to metal-porphyrin, means that the deprotonation of porphyrin takes place. The spectral characteristics of THPP in neutral and in basic Triton X-100 micelle are similar to that in THF and in basic aqueous, indicating that the solubilizing location of THPP changes from the inner to the outer of the Triton X-100 micelle. The result reveals that varying pH could control the transmembrane process of THPP. The kinetic study of porphyrin incorporating with Cu(II) shows that metalation rate of porphyrin increases with the increasing of pH, confirming the existing of the transmembrane process of THPP.Chapter3 The interaction of meso-tetrakis (4-hydroxyphenyl) porphyrin (THPP) with human serum albumin (HSA) at pH=3 was investigated by UV-vis and fluorescence spectrum in mixed solvent solution(R=0.1,R==VDMso:VWater). A 1:1 stoichiometry noncovalent THPP-protein complex was monitored in the system and its association constant K=3.65X 10 M' was calculated by the change of spectral characteristics. It is the binding of HSA with neutral form of THPP that promoted deprotonation of THPP from acidic form to neutral form by a distinct equilibrium, H4THPP =^H2THPP -* H2THPP-protein, as detected by UV-visible spectrum. Hydrophobic interactions seemed to play the major role in the assembly process. The interaction of THPP and HSA was likely to be in domain IIA or IIIA where its hydrophobic interior accounted for the spectral shift. Fluorescence quenching of Trp214 clearly put into evidence a mechanism of energy transfer from Trp214 residue to neutral form of THPP at pH=3. Furthermore, the ionic strength increased by adding of NaCl to the system of H2THPP-protein may pose an obstacle to the formation of the H2THPP-protein complex and promote the aggregation of THPP.Chapter4 The interactions of meso-tetrakis(4-N-methylpyridiumyl) porphyrin (TMPyP) with calf thymus DNA (ctDNA) was investigated by UV-vis and fluorescence spectrum in the absence and presence of p-cyclodextrin (P-CD) and its derivatives including hydroxypropyl-p-cyclodextrin (HP-p-CD) and sulfobutylether-P-cyclodextrin (SBE-p-CD). The signals of resonance light-scattering(RLS) was almost indentical when varied the concentrations of ctDNA, which revealed that the main binding model of TMPyP with ctDNA may be intercalation model rather than outside self-stacking model. Moreover, P-CD and its derivatives can inhibit the intercalation of TMPyP into ctDNA double helix.The stronger the inclusion ability of TMPyP with CDs, the bigger the influence on the binding constants and binding sites as the TMPyP can enter into the hydrophobic cavity of CDs. Chapter5 Two kinds of metal derivatives of meso-tetrakis (4-N-ethylpyridiumyl) porphyrin (TEPyP), Zn-TEPyP and Cu-TEPyP, were synthesized. The interactions of Zn-TEPyP and Cu-TEPyP with calf thymus DNA (ctDNA) in the neutral aqueous solution were investigated by UV-vis , fluorescence and resonance light-scattering (RLS) spectrum, respectively.